Hepatitis B virus (HBV) infection is a serious public health problem worldwide. HBV infection is an important cause of chronic hepatitis B, cirrhosis and hepatocellular carcinoma (Fattovich G. J Hepatol 2008; 48: 335-352). Clinically, the treatment of chronic HBV infection mainly relies on the common drugs nucleoside analogues and interferons. Nucleoside analogs cannot completely remove cccDNA in liver cells, and a long-term use of them may lead to occurrence of drug-resistant mutants and rebounding after drug discontinuance (Kwon H, Lok A S Nat Rev Gastroenterol Hepatol 2011; 8: 275-284). Interferon is not suitable for asymptomatic HBV carriers. Among patients with chronic HBV, the HBeAg seroconversion rate after use for half a year is only 33%, moreover, the interferon has high side effect, which also restricts its applications (Tang S X, Yu G L. Lancet 1990; 335 (8684): 302).
At present, the widely used hepatitis B protein vaccine can produce protective antibodies by inducing humoral immunity, to achieve the goal of prevention. A large number of studies have shown that protective antibodies can only eliminate the extracellular virus particles. The elimination of the intracellularly infected virus mainly relies on specific cellular immune response, helper T cells, IFN-γ and other Th1-type cell factors producing from CD4+ T cells, in particular virus-specific cytotoxic T lymphocytes (CTL) (Chin R, Lacamini S. Rev Med Viorl 2003: 13 (4): 255-72). The cellular immune response will directly affect the prognosis of hepatitis B. Therefore, an ideal hepatitis B vaccine should induce the specific humoral and cellular immunity, to break through immune tolerance of hepatitis B.
Currently, the research and development of therapeutic vaccines for hepatitis B focus on HBsAg. Through overcoming the immune tolerance and producing anti-HBsAg antibodies, it can achieve the effect of immune clearance, for example, HBsAg-immunoglobulin complexes by Wen Yumei (Xu D Z, Zhao K, et al. PLoS ONE, 2008, 3: e2565), high-dose HBsAg vaccine by Zhang Yijun (Zeng Ying, Zhang Yijun, et al, Guangdong Medical Journal, Issue 7, Volume 24, 2003, P740-706) are based on this principle. But the therapeutic effect of the two vaccines is still unclear according to the latest clinical data.
Studies have shown that the subtype of anti-HBsAg antibody for patients with chronic hepatitis B infection is mainly IgG4, while the subtype of anti-HBsAg antibody for patients with cure of hepatitis B infection is mainly IgG1(≧IgG4), suggesting that Th1 type IgG1 antibody subtype plays an important role in the process of clearing hepatitis B infection. The evaluation on Th1 type antibody subtype higher or lower than Th2 type antibody subtype can prompt the curative effect of hepatitis B (S. Rath, et al. Clin. exp. Immunol. (1988) 72, 164-167). Meanwhile, the anti-HBcAg antibody subtype for patients with hepatitis B infection is IgG1>IgG3>IgG4, but for the patients with cure of hepatitis B infection, it is converted to IgG3>IgG1>IgG4, suggesting that the conversion of anti-HBcAg, especially the conversion of anti-HBcAg antibody subtype is possibly closed related to the treatment of hepatitis B (Chien-Fu Huang, et al Cellular & Molecular Immunology 2006; 3 (2): 97-106).
In addition, studies have shown that the expression of dendritic cells (pDC) surface receptor TLR9 is down regulated for chronic HBV carriers and patients with chronic hepatitis B, which leads to the body's immune tolerance to HBsAg and unable to produce hepatitis B surface antibody or cellular immunity against HBsAg (Q. Xie et al. Microbes and Infection 11 (2009) 515-523).
In the U.S. Pat. No. 4,547,367, HBcAg particle was used to treat/prevent HBV infection and HBV-mediated diseases. The immunization of chimpanzees using HBcAg particles can protect chimpanzees from HBV infection. Besides, the immunization of newborns produced by hepatitis B carrier mothers using HBcAg particle and HBsAg particle could produce high-titer anti-HBsAg and anti-HBcAg antibody, and no HBV infection was found in the 18-month monitoring. But this patent did not provide the evidences for the conversion of anti-HBcAg antibody subtype, nor provide the the direct evidences for the treatment of HBV infection and HBV-mediated diseases.
In the patent WO2007/031334, the components of hepatitis B therapeutic vaccine were protected, including HBsAg, HBcAg and one kind of saponin adjuvant. CpG-ODN can be used as a common adjuvant, but the hepatitis B therapeutic vaccine should be used in combination with nucleoside analogues for combined treatment, to break through immune tolerance to hepatitis B and the e antigen negative-conversion rate was only 25%.